Wireless telecommunications are experiencing a critical stage as a change from second generation networks to third generation networks is taking place. At least for some time, networks of both generations are being used in parallel, because teleoperators have invested in network equipment and end-users in telephones. In addition, it will take time before the operators can make the networks of the new system geographically comprehensive. The most known of the second generation systems is probably the GSM system and its modifications, such as EDGE (Enhanced data rates for GSM evolution). Of the third generation systems, systems based on the WCDMA technology are expected to achieve the most prominent position. Thus, there is a need to implement a multi-mode base station which serves both the GSM networks and the WCDMA networks. Such a multi-mode base station will be able to cover several networks in a cost-effective manner. A problem arises, however, from the fact that the clock frequencies of different systems differ from each other. This can be solved by each system having a clock of its own. A problem then arises from the fact that clock frequencies are typically implemented by oven-controlled oscillators which are large and expensive components.